11/18 Cerebellum Lecture

Question 1

THE CEREBELLUM ACTS AS A

_____ .

Answer 1

COMPARATOR,
middle management

The cerebellum takes the command from the cerebral cortex and makes the fine adjustments needed for efficient motor function.

Question 2

The cerebral cortex gives the command to initiate voluntary movement.

Answer 2

But, it doesn’t give any particular guidance on how to make the movement smooth and coordinated.
This is where the cerebellum comes in.

Question 3

Neurons in the ____ carry proprioceptive information from the ____ via several different pathways to the cerebellum.

Answer 3

Neurons in the DRG carry proprioceptive information from the Muscle via several different pathways to the cerebellum.

Question 4

The Pathway

Answer 4

The cerebral cortex sends a message to motor neurons in the spinal cord. These innervate the muscle and it contracts.

There is a parallel pathway from the cortex to the cerebellum. This is not a direct pathway and involves relays in the Basilar Pons.

Now the cerebellum knows what the cortex is planning.
It needs some additional information, however, before making adjustments.

It needs to know something about where the body is in space, as well as the status of the muscles at an instant in time (i.e., proprioceptive information).

Neurons in the dorsal root ganglia carry proprioceptive information from the muscle via several different pathways to the cerebellum.

Now the cerebellum can compare the command from the cortex with the current status of the muscle.

The output of the cerebellum is to brainstem nuclei that project to the spinal cord to adjust the activity of motor neurons as necessary.

As middle management, the cerebellum also projects back to the cortex in another indirect route.

Question 5

The output of the cerebellum is to _____ that project to the _____ to adjust the activity of motor neurons as necessary.

Answer 5

The output of the cerebellum is to Brainstem Nuclei that project to the Spinal Cord to adjust the activity of motor neurons as necessary.

Question 6

FUNCTION OF THE CEREBELLUM:

Cerebellum receives sensory information from ____ in muscles and joints and other nuclei in the ____ which provide information about the state of contraction of the individual muscles or the position of the body in space.
Uses this information to do 6 things….

Answer 6

Cerebellum receives sensory information from proprioceptors in muscles and joints and other nuclei in the brainstem which provides information about the state of contraction of the individual muscles or the position of the body in space.

Uses this information to:

1. Control posture & balance
2. Coordinate sequential movements.
3. Coordinate rapidly alternating movements (Diadocokinesis).
4. Regulate Reflexes
5. Involved in motor learning
6. Plays a role in higher cognitive functions (e.g., attention, planning movements).

Question 7

Dysmetria

Answer 7

Inability to fix the range of movement in muscular activity.

Movements are made with more force than necessary.

Question 8

Ataxia

Answer 8

Inability to coordinate movement

Question 9

Intention Tremor

Answer 9

A tremor that gets worse when a person is moving.

Question 10

Diadocokinesis

Answer 10

the normal ability to perform rapidly alternating muscular movements, such as flexion and extension.

Question 11

The Cerebellum controls posture & balance through connections with ______ .

Answer 11

the vestibular system

Question 12

the cerebellum has several functions …..

Answer 12

It controls posture and balance through connections with the vestibular system.

One function of the cerebellum is controlling eye movements.
Executing Complex, Smooth Pursuit Eye Movements

It is essential for performing sequential movement, such as reaching out for something requiring contraction of shoulder, elbow, wrist, and digital muscles in a specific sequence.

Several terms are applied when movement is not smooth:

Dysmetria means the range of movements is not properly set. Movements may be made very fast, or with more force than necessary.

Ataxia is the inability coordinate movement.

With cerebellar lesions, there may be an Intention Tremor as the limb moves back and forth trying to home in on a target.

The cerebellum is essential for performing alternating movements like using a screwdriver or opening a door.

It regulates reflexes.
In primates, in particular, it is involved in motor learning. The first time you ride a bike you may be very clumsy, but ultimately you become very smooth and coordinated. That’s because there are circuits that allow the cerebellum to learn and become more efficient.

Finally, it plays a role in higher cognitive functioning, such as attending to our environment or in planning movements.

Question 13

Cerebellar lesion that effects the eye:

Answer 13

Saccadic overshoot

Dysmetria

Question 14

Saccadic overshoot

Dysmetria

Answer 14

Cerebellar lesion effecting the eye

Question 15

Execute Complex, Smooth Pursuit Eye Movements

Answer 15

One function of the cerebellum is controlling eye movements.

An example of an individual following a moving target with their eyes.

The object enters their field of view and the eyes follow it smoothly.

Then the target stops abruptly.
The normal response is for the eyes to continue in anticipation of the object continuing along its path.

Normally, the eyes will rapidly fixate on the now stationary target.

In individuals with a cerebellar lesion, the eyes overshoot in the opposite direction, and then come back and so forth until they ultimately land on the object.
This is an example of dysmetria in which the eyes move through a greater range of motion than necessary.

Question 16

4 CEREBELLAR NUCLEI: WITHIN THE WHITE MATTER CORE OF CEREBELLUM

Answer 16

FASTIGIAL N.
DENTATE N.

The 2 INTERPOSED NUCLEI:
GLOBOSE N.
EMBOLIFORM N.

Question 17

Cerebellar Peduncles

Details

Answer 17

Cerebellar Peduncles (Inferior, Middle, Superior) = 
Fiber tracts that connect cerebellum to brainstem.  

They are made up of:

1. Axons entering the cerebellum that originate in the spinal cord or other parts of the brainstem (e.g., medulla, pons). These axons will terminate in the cerebellar nuclei and cerebellar cortex.
2. Axons leaving the cerebellum that originate in one of the cerebellar nuclei. These are destined for brainstem targets.

Question 18

Middle Cerebellar Peduncle

Answer 18

Only carries information TO cerebellum.

MCP connects the pons to the cerebellum.

Largest peduncle.

Exclusively an input pathway.

Pathway crosses in the pons.

Question 19

Inferior Cerebellar Peduncle

Answer 19

Mostly carries information TO cerebellum.

Carries some info from the cerebellum

ICP connects the spinal cord & medulla to the cerebellum.

Mainly an input pathway.

Question 20

Superior Cerebellar Peduncle

Answer 20

Mostly carries information FROM cerebellum.

Carries some info to the cerebellum.

SCP connects the cerebellum to the brainstem and diencephalon.

Axons leaving the cerebellum cross in the midbrain.

Major output pathway from the cerebellum to the brainstem.

Question 21

The Largest Peduncle

Answer 21

Middle Cerebellar Peduncle

Question 22

The smallest of the peduncles is the _____ .

Answer 22

inferior cerebellar peduncle (ICP).

Question 23

Major output pathway from the cerebellum to the brainstem?

Answer 23

Superior Cerebellar Peduncle

Question 24

Connects the pons to the cerebellum.

Answer 24

Middle Cerebellar Peduncle

Question 25

Mainly an input pathway.

Answer 25

Inferior Cerebellar Peduncle

Question 26

Connects the spinal cord and medulla to the cerebellum.

Answer 26

Inferior Cerebellar Peduncle

Question 27

CEREBELLAR PEDUNCLES: | Long Summary

Answer 27

The smallest of the peduncles is the inferior cerebellar peduncle (ICP). It extends from the rostral medulla to the cerebellum. This is a pathway that brings information into the cerebellum from the spinal cord and medulla. It courses a bit inferior to the MCP. The largest cerebellar peduncle is the middle cerebellar peduncle (MCP). The middle cerebellar peduncle connects the pons and the cerebellum. It also is an input pathway carrying axons from neurons in the basilar pons into the cerebellum. The superior cerebellar peduncle arises from the rostral pole of the cerebellum and courses toward the midbrain. This is the major output pathway of the cerebellum.

Question 28

The major output pathway of the cerebellum.

Answer 28

superior cerebellar peduncle

Question 29

CEREBELLAR CORTEX

Answer 29

The cerebellar cortex is highly infolded forming deep ridges. If it was completely unfolded it would extend up to 1 meter in length. This clearly reflects the importance of this structure in brain function.

Question 30

Primary fissure

Answer 30

Divides the cerebellum into Anterior and Posterior lobes.

Question 31

Flocculonodular lobe

Answer 31

The most primitive part of the cerebellum. very small lobe.

Question 32

Rostral-Caudal Organization

Answer 32

Primary fissure: Divides the cerebellum into Anterior and Posterior lobes. On the inferior view, a third very small lobe is defined as the Flocculonodular lobe; most primitive part of the cerebellum.

Question 33

Prime example of a disabled cerebellum:

Answer 33

a drunk person

Question 34

Vermis

Answer 34

Narrow midline portion that extends through all lobes.

Question 35

3 cerebellar nuclei appear to align with the 3 sagittal divisions of the cerebellar cortex.

Answer 35

Fastigial nucleus in the vermis, i Inerpositus nuclei in the medial hemisphere Dentate nucleus in the lateral hemisphere.

Question 36

The most medial cerebellar nuclei

Answer 36

Fastigial nuclei

Question 37

ORGANIZATION IN PROJECTION FROM CORTEX TO CEREBELLAR NUCLEI: FLOCCULONODULAR LOBE AND VERMIS

Answer 37

FASTIGIAL NUCLEUS

Question 38

ORGANIZATION IN PROJECTION FROM CORTEX TO CEREBELLAR NUCLEI: MEDIAL HEMISPHERE

Answer 38

INTERPOSED NUCLEI | GLOBOSE & EMBOLIFORM

Question 39

ORGANIZATION IN PROJECTION FROM CORTEX TO CEREBELLAR NUCLEI: LATERAL HEMISPHERE

Answer 39

DENTATE NUCLEUS

Question 40

CEREBELLAR HISTOLOGY

Answer 40

PIAL SURFACE WHITE MATTER CORE

Question 41

PIAL SURFACE

Answer 41

MOLECULAR LAYER PURKINJE CELL LAYER GRANULE CELL LAYER

Question 42

PURKINJE CELL LAYER

Answer 42

Only cell with an axon that leaves the cerebellar cortex. Terminates in one of the cerebellar nuclei; dependent on sagittal zone in which it is located. Inhibitory to target neurons in the cerebellar nuclei (GABAergic).

Question 43

GRANULE CELL

Answer 43

Parallel fibers are intrinsic to the cortex. Excitatory to Purkinje cells These cells are interesting in that they stay in the sagittal plane.

Question 44

BASIC CEREBELLAR CIRCUIT

Answer 44

Cerebellar Cortex: Perkinje cells - --> Cerebellar Nuclei - -->Brainstem Nuclei, Thalamus - --> Spinal cord, Cerebral cortex

Question 45

Expounded CEREBELLAR CIRCUIT

Answer 45

Cerebellar Cortex: Perkinje cells. (This projection has a precise sagittal organization. Vermal PK cells project to fastigial nucleus, medial hemisphere to interposed, and lateral hemisphere to dentate.) ---> Cerebellar Nuclei Axon leaves the cerebellum via the superior cerebellar peduncle - --> Brainstem Nuclei, Thalamus (e. g., Reticular Formation, Red Nucleus, Vestibular Nuclei). ---> Spinal cord, where they regulate alpha and gamma motor neurons. Cerebral cortex to provide feedback to motor neurons giving rise to corticospinal tract.

Question 46

CEREBELLAR CIRCUIT: | long version

Answer 46

At the simplest level, are the neurons in the cerebellar nuclei. These neurons have axons that leave the cerebellum. They synapse on neurons in several different brainstem nuclei that in turn give rise to the descending pathways, such as the reticular formation and vestibular nuclei. They are excitatory to these neurons. These brainstem nuclei, in turn, project to the spinal cord, where they synapse on interneurons that regulate alpha motor neurons and thus motor activity. This is a nice basic circuit, but it needs to be regulated. Nuclear neurons are very active and sometimes they have to be shut down. That is the role of the Purkinje cell. Purkinje cells and nuclear neurons receive the same information, although at slightly different times. The axons of these neurons leave the cerebellar cortex, and inhibit neurons in the cerebellar nuclei. So what regulates the activity of Purkinje cells? Afferents from different regions of the CNS carrying information either from the periphery or from the cerebral cortex.

Question 47

AFFERENT INPUTS TO CEREBELLUM

Answer 47

MOSSY FIBERS | CLIMBING FIBERS

Question 48

MOSSY FIBER

Answer 48

Source: Neurons Located In Various Nuclei In The Spinal Cord And Brainstem (e.g., Vestibular Nuclei, Pontine Nuclei, Neurons in the spinal cord). Morphology: Complex Large Terminals (10-12 uM). Excitatory To Granule Cells (Glutamate) Mossy fibers synapse on neurons in the Granule Cell Layer. The granule cell sends its axon into the molecular layer where they terminate on Purkinje cells. These axons are called Parallel Fibers.

Question 49

mossy fiber details

Answer 49

A histological preparation of a mossy fiber (MF). The long black structure is the MF axon that is connected to a neuron located outside the cerebellum. This axon entered the cerebellum through either the inferior or middle cerebellar peduncle and coursed to the cortex after giving off a branch in the cerebellar nuclei. Once it reached the cerebellum, the axon terminals were formed. Mossy fibers originate from neurons located throughout the CNS, including Clarke’s Nucleus in the spinal cord and the external cuneate nucleus in the brainstem. Remember: these nuclei relay proprioceptive information from muscles to the cerebellum. Mossy fiber afferents also come from neurons located in the vestibular nuclei, which are essential for fulfilling the role of the cerebellum in balance. Finally, the pontine nuclei in the basilar pons also are a source of afferents to the cerebellum. These relay information from the cerebral cortex. Thus, mossy fibers are essential components of the “comparator circuitry.” Morphogically, the axon terminals are large, measuring 10-12 um in diameter. Mossy fibers are excitatory to neurons in the granule cell layer. Neurons in this layer relay the excitatory information to the Purkinje cell. The axons of these second order neurons are called Parallel Fibers.

Question 50

CLIMBING FIBER

Answer 50

Sole Source: Inferior Olivary Complex Characteristics: One-to-one Relationship With Purkinje Cell. Courses Along Primary Dendrites Giving Off Varicosities that Synapse With Primary and Secondary Dendrites. Powerful Excitatory Input To Purkinje Cells (Glutamate) Climbing Fibers “Climb” Along The Primary And Secondary Dendrites Of Purkinje Cells.

Question 51

CLIMBING FIBER | detailsss...

Answer 51

A climbing fiber looks very different from a mossy fiber. These axons arise from neurons located in only 1 place – the inferior olivary nucleus in the medulla. No other areas of the brain give rise to climbing fibers. These axons have unique relationship with Purkinje cells. They form a 1 to 1 relationship. That is, Purkinje cells receive input from only 1 climbing fiber. There is no convergence of information from different olivary neurons. This is unique and there are no other neurons with this type of relationship. Unlike Mossy fibers that have a relay in the granule cell layer, climbing fibers go directly to the Purkinje cell where the literally climb along the dendrites of the neuron. They are a powerful source of excitation to the Purkinje cell releasing glutamate. Because it is a one to one relationship, all of the terminals release their transmitter at the same time depolarizing the entire dendritic tree. This is important.

Question 52

AFFERENTS TO THE CEREBELLUM Longggg version

Answer 52

Inputs. There are 2 anatomically distinct afferents that project to the cerebellum: mossy fibers and climbing fibers. As both afferents enter the cerebellum, they give off branches to the cerebellar nuclei that are excitatory to nuclear neurons. The same afferents continue on to the cortex. This is where the 2 afferent systems differ. Climbing fibers project directly to Purkinje cells and provide a direct, powerful excitation of these neurons. The information carried by mossy fibers does not go directly to Purkinje cells, but is relayed by the granule cell. The axon of the granule cell, the parallel fiber, enters the molecular layer, runs parallel from medial to lateral (hence its name) passing through the dendrites of numerous Purkinje cells. Synaptic junctions between parallel fibers and the spines of Purkinje cells are excitatory.  

Question 53

Mossy Fiber Input to Sagittal Zones of the Cerebellum

Answer 53

????

Question 54

FUNCTIONAL DIVISIONS OF THE CEREBELLUM

Answer 54

Spinocerebellum Pontocerebellum Vestibulocerebellum

Question 55

VESTIBULOCEREBELLUM

Answer 55

FLOCCULONODULAR LOBE Function: Control balance and equilibrium (in trunk and axial muscles especially). Input: Neurons related to vestibular system. Axons of these neurons enter cerebellum via ICP. Neurons in the Fastigial nucleus. Purkinje cells in flocculonodular lobe. Neurons in the vestibular nuclei which project to spinal cord. Excitatory to interneurons that regulate activity of α and λ motor neurons in ventral horn of spinal cord.

Question 56

SPINOCEREBELLUM

Answer 56

Vermis and adjacent medial portion of hemisphere. FUNCTION: Control muscle tone and muscle synergy (coordination across and between joints) Input: Proprioceptors in muscles via nuclei in spinal cord and brainstem. Carry information on position or tension in muscle or tendon. This is UNCONSCIOUS PROPRIOCEPTION. Interposed Nuclei, Fastigial Nucleus, Purkinje cells in the vermis, Purkinje cells in the medial hemisphere

Question 57

SPINOCEREBELLUM: Interposed Nuclei

Answer 57

Interposed Nuclei - ---> Axons leave via SCP and synapse on neurons in Red Nucleus or Ventral Lateral Thalamic nucleus (NOT the VPL). - --> Spinal cord (rubrospinal tract) or back to motor cortex (thalamocortical axons)

Question 58

SPINOCEREBELLUM: Fastigial Nucleus

Answer 58

Fastigial Nucleus - --> Axons leave via ICP and synapse on neurons in reticular formation - --> Spinal cord to interneurons to control motor neurons via reticulospinal tract.

Question 59

ASCENDING AXONS FROM THE INTERPOSED NUCLEI

Answer 59

Some axons terminate in Red Nucleus. These neurons give rise to the rubrospinal tract that descends to contralateral spinal cord. Returns to same side of body from which PSCT originated. Cerebellum controls ipsilateral side of body. Remaining axons in SCP continue on to contralateral VL complex of thalamus. Neurons in the thalamus project to pyramidal neurons in the motor cortex to provide feedback on state of movement. Axons of pyramidal neurons project to spinal cord via corticospinal tract.

Question 60

ASCENDING AXONS FROM INTERPOSED NUCLEI LONG VERSION

Answer 60

Ascending axons arising from the interposed nuclei. These axons leave the cerebellum via the SCP, cross in the rostral pons in the decussation of the SCP and ascend to the midbrain and diencephalon. The majority of axons terminate in the Red Nucleus to modulate the activity of neurons giving rise to the rubrospinal tract. There is an influence of the cerebellum on neurons that project to the spinal cord to influence motor neurons in the ventral horn. These axons return to the same side of the body from which proprioceptive information carried by the posterior spinocerebellar tract originated. The cerebellum controls the ipsilateral side of the body. Finally, a few axons continue to the thalamus where they terminate in the ventral lateral (NOT ventral POSTERIOR lateral) nucleus. The axons of VL neurons project back to motor cortex to provide feedback to “the boss”. These neurons in the motor cortex project back to the spinal cord via the corticospinal tract.

Question 61

PONTOCEREBELLUM

Answer 61

= Lateral portion of hemisphere FUNCTION: Fine coordination of movement. Planning and controlling movement, especially distally. Input: Indirectly from neurons in cerebral cortex. Neurons in cerebral cortex synapse on neurons in the basilar pons. Neurons in the basilar pons cross the midline and project to the lateral part of the cerebellum via the MCP. Dentate Nucleus ---> Majority of neurons in the dentate nucleus synapse on neurons in VA/VL thalamus that project to cortex (feedback to motor cortex) to influence corticospinal tract. Purkinje cells in the lateral hemisphere synapse on neurons in the dentate nucleus. Inhibitory input (GABAergic)

Question 62

CORTICO-PONTO-CEREBELLAR INPUT

Answer 62

Cortical Input Derived From All Areas Of Cortex Synapse On Pontine Neurons Axons Of Pontine Neurons Cross Midline And Enter Contralateral Cerebellum Via MCP.

Question 63

CORTICO-PONTO-CEREBELLAR INPUT Details

Answer 63

Input to the lateral hemisphere. Axons from all areas of the cortex descend and synapse on neurons in the pontine nuclei located within the basilar pons. The axons of these neurons cross the midline and form the large middle cerebellar peduncle which relays cortical information to the lateral hemisphere.

Question 64

PROJECTIONS OF DENTATE NUCLEUS | - LATERAL HEMISPHERE

Answer 64

Axons leave via ipsilateral SCP, decussate in rostral pons. Tract continues from decussation and terminate in contralateral Red nNucleus. Axons of olivary neurons cross the midline and project to the cerebellum as climbing fibers. Feedback loop between cerebellum red nucleus, and inferior olive. Majority of axons continue on to VL/VA complex of thalamus. Neurons in the thalamus project to pyramidal neurons in the motor and premotor cortex to provide feedback on state of movement. Axons of pyramidal neurons project to spinal cord via corticospinal tract.

Question 65

PROJECTIONS OF DENTATE NUCLEUS - LATERAL HEMISPHERE Dteails

Answer 65

The projection of the dentate nucleus is very similar to that of the interposed nuclei with the exception that there is not a descending limb. The axons leave via the ipsilateral SCP and decussate in the rostral pons. The Red Nucleus neurons that receive this input are NOT the ones that give rise to the rubrospinal tract!!! Rather, these red nucleus neurons terminate in the Inferior Olive, the source of climbing fibers to the cerebellum. Axons of olivary neurons cross the midline and project to the cerebellum as climbing fibers. This pathway represents a feedback loop between the cerebellum, red nucleus, and inferior olive that regulates climbing fiber activity. The majority of the dentate nucleus axons continue on to the VL nucleus of the thalamus. These axons project to the motor cortex to provide feedback to neurons giving rise to the corticospinal tract.

Question 66

Flocculonodular Lobe: | ALL THE MAIN POINTS

Answer 66

FUNCTION: Maintenance Of Equilibrium MOSSY FIBER INPUT: Vestibular Neurons OUTPUT: Fastigial Nucleus To Vestibular Nucleus

Question 67

Medial Hemisphere

Answer 67

FUNCTIONS: - Descending Tract: Postural Adjustments - Ascending Tract (Interposed): Via Rubrospinal And Corticospinal Tracts MOSSY FIBER INPUT: - Spinal Cord - Reticular Formation - Pontine Nuclei (Relay from cerebral cortex) OUTPUT: Fastigial & Interposed Nuclei To: Descending Tract: - Vestibular Nuclei (Fastigial) - Reticular Formation (Interposed) Ascending Tract (Interposed): - Red Nucleus - VA/VL Thalamus

Question 68

Lateral Hemisphere

Answer 68

FUNCTION: Planning & Programming of Voluntary Movements, esp. Learned, Skillful Movements that become More Rapid with Practice. MOSSY FIBER INPUT: Corticopontine Axons OUTPUT: - Dentate Nucleus - Red Nucleus - VA/VL Thalamus

Question 69

CLIMBING FIBER INPUT: INPUTS TO THE INFERIOR OLIVE

Answer 69

- SPINAL CORD - CEREBRAL CORTEX - VESTIBULAR NUCLEI - RED NUCLEUS - RETICULAR FORMATION - CEREBELLUM

Question 70

CLIMBING FIBERS PLAY A ROLE IN ERROR DETECTION

Answer 70

Mossy Fibers, on the other hand, are more associated with normal, adapted-to movements.

Question 71

SUMMARY CEREBELLAR CIRCUIT: PURKINJE CELLS

Answer 71

Only neurons with an axon that leaves the cerebellar cortex. Role is to modulate the output of nuclear neurons.

Question 72

SUMMARY CEREBELLAR CIRCUIT:

Answer 72

Carry output of the cerebellum to brainstem nuclei and motor cortex. Without nuclear neurons, cerebellum has no control over movements.

Question 73

SUMMARY CEREBELLAR CIRCUIT: INPUT TO THE CEREBELLUM

Answer 73

Two afferent systems: Mossy Fibers & Climbing Fibers Collaterals of afferents to the cerebellum first synapse in the cerebellar nuclei before continuing on to the cerebellar cortex. Purkinje cells in cortex project to areas of nuclei receiving same afferents.

Question 74

SUMMARY CEREBELLAR CIRCUIT: There is a precise ____-to-____ _____ organization in the projection between the cerebellar ___ and the cerebellar ____.

Answer 74

medial-to-lateral sagittal There is a precise medial to lateral sagittal organization in the projection between the cerebellar Cortex and the cerebellar Nuclei.

Question 75

SUMMARY CEREBELLAR CIRCUIT: Fastigial nucleus

Answer 75

Flocculonodular lobe and Vermis

Question 76

SUMMARY CEREBELLAR CIRCUIT: Globose & Emboliform nuclei (interposed nuclei)

Answer 76

Medial hemisphere

Question 77

SUMMARY CEREBELLAR CIRCUIT: Dentate nucleus

Answer 77

Lateral hemisphere

Question 78

Collaterals of afferents to the cerebellum first synapse in the ____ before continuing on to the ____.

Answer 78

Collaterals of afferents to the cerebellum first synapse in the cerebellar nuclei before continuing on to the cerebellar cortex.

Question 79

OUTPUT AND FUNCTION OF CEREBELLAR NUCLEI:

Answer 79

The vast majority of axons arising from neurons in the cerebellar nuclei leave via the superior cerebellar peduncle. The vast majority of neurons in the nuclei give rise to an excitatory output which projects to nuclei in brainstem that are directly involved in controlling movement (e.g., vestibular nuclei, red nucleus) or provide feedback to the cerebral cortex via the thalamus.

Question 80

ALCOHOL AS A NEUROTOXIN IN THE ADULT AND DEVELOPING CEREBELLUM ACUTE CHANGES:

Answer 80

The effect is primarily on Purkinje cells in the anterior lobe. 1. Effect is on voltage-sensitive ionic conductances. 2. It augments the opening of Cl- channels by GABA leading to hyperpolarization of the Purkinje cell. *Ethanol in alcoholic beverages takes the purkinje cells out of the curciut. Purkinje cells are inbitory and have many GABA receptors. This is why.....

Question 81

ALCOHOL AS A NEUROTOXIN IN THE ADULT AND DEVELOPING CEREBELLUM CHRONIC USE:

Answer 81

CHRONIC USE CAUSES DEATH OF PURKINJE CELLS IN ANTERIOR LOBE. Decreases levels of cGMP which changes cellular metabolism and alters cellular function.

Question 82

ALCOHOL AS A NEUROTOXIN IN THE ADULT AND DEVELOPING CEREBELLUM ADULT CLINICAL SIGNS:

Answer 82

1. Gait ataxia: stiff legged gait with small shuffling steps 2. Increased tone in extensor muscles. (change in input to reticular formation and vestibular nuclei, which alters input to motor neurons.)

Question 83

ALCOHOL AS A NEUROTOXIN IN THE ADULT AND DEVELOPING CEREBELLUM DEVELOPMENTAL EFFECTS: CLINICAL SIGNS

Answer 83

1. DELAYS IN MOTOR DEVELOPMENT 2. PROBLEMS WITH FINE MOTOR TASKS 3. TREMORS 4. ATAXIA

Question 84

ALCOHOL AS A NEUROTOXIN IN THE DEVELOPING CEREBELLUM DEVELOPMENTAL EFFECTS: ANATOMICAL

Answer 84

DENDRITIC TREE HAS FEWER BRANCHES & SPINES

Question 85

AUTISM

Answer 85

AUTISM IS A DEVELOPMENTAL, NOT A PSYCHOLOGICAL, DISORDER WITH DEFICITS IN BRAINSTEM, MIDBRAIN, FRONTAL LOBE, AND CEREBELLUM IN CEREBELLUM, OFTEN A DECREASE IN SIZE OF VERMAL LOBULES VI & VII. ALSO SEE ABNORMAL LEVELS OF SEROTONIN.

Question 86

MOTOR vs ATTENTION REGIONS OF THE CEREBELLUM

Answer 86

THEORY: CEREBELLUM PROVIDES INPUT TO MOTOR-ATTENTIONAL AREAS OF BRAIN, SUCH AS RETICULAR FORMATION. ONE STUDY HAS SHOWN THAT MOTOR CONTROL AND ATTENTION INDEPENDENTLY ACTIVATE DIFFERENT REGIONS OF THE CEREBELLUM. ATTENTION AREA IS IN AREA IMMEDIATELY POSTERIOR TO PRIMARY FISSURE - AND ADJCENT HEMISPHERE (MOST RECENTLY EVOLVED AREAS OF CEREBELLUM) THIS IS RELEVANT TO AUTISM AS A MAJOR PROBLEM IS THE INABILITY TO SHIFT ATTENTION IN A “COORDINATED” MANNER. THIS SUGGESTS THE CEREBELLUM PLAYS A ROLE IN HIGHER COGNITIVE FUNCTION.

Question 87

THE CEREBELLUM OF MALE MUSICIANS IS 5% LARGER THAN THOSE OF MALE NON-MUSICIANS.

Answer 87

CONCEPT: | MANY YEARS OF PRECISE FINGER EXERCISE HAD STIMULATED EXTRA NEURAL GROWTH IN THE CEREBELLUM